The goal of this program is to improve population health by assisting clinicians and their patients to address the challenges of individualizing breast cancer treatment for women with favorable prognosis. Project 1 is concerned with the management of locoregional therapy; Project 2 with the management of systemic therapy; and Project 3 aims to evaluate a Patient Intervention decision tool. Common elements across projects include being informed by an overall conceptual model, presenting similar constructs, and sharing a methodology requiring the use of patient surveys, and the merging of -Surveillance, Epidemiology and End Results (SEER) Registry clinical data elements with information obtained from patient surveys. Finally, Projects 1 and 2 propose surveying attending clinicians of patient participants. Core B will support these cross-project activities by: overseeing the development and use of consistent survey measures, maximizing the efficiency of a uniform strategy for SEER-based sampling and rapid case ascertainment; coordinating patient and clinician survey data collection protocols; and, developing standardized methods for merging datasets. This Core will have an opportunity to advance innovative population-based methods regarding measurement reliability, validity, and durability. The specific aims of Core B are as follows: Aim 1: Develop a bank of survey measures and items that will provide consistency in the measurement of common constructs across studies. Aim 2: Develop and implement a uniform strategy for SEER-based sampling, rapid case ascertainment, and the integration of clinical data collected through routine surveillance activities. Aim 3: Coordinate the development and implementation of patient and clinician surveys to maximize participant rates, minimize the number of unique patients required across studies, and minimize the administrative burden on SEER sites. Aim 4: Validate key clinical information collected by SEER under the new SEER 2010 data requirements against patient self-report (e.g., receipt of radiation) and other objective measures (e.g., 21 gene assay). Aim 5: Further inform our measurement of